"In order to see signs of planets in the dust, the alien astronomers would need to tune their instruments to spot the smallest dust. Landgraf studies this, too, bits that are just one-hundredth of a millimeter, or dozens of times tinier than a typical grain of sand. It is everywhere in our solar system, zipping around ten times faster than a rifle bullet."

They don't need an alien astronomer. My mother could find it just fine herself without any aid from the Swiss opticians. Now I know why the carpet was never vacuumed enough to suit her.